This is useful when we wish to have a channel frozen for a specific
amount of blocks after its confirmation. This could also be done with an
absolute thaw height, but it does not suit cases where a strict block
delta needs to be enforced, as it's not possible to know for certain
when a channel will be included in the chain. To work around this, we
add a relative interpretation of the field, where if its value is below
500,000, then it's interpreted as a relative height. This approach
allows us to prevent further database modifications to account for a
relative thaw height.
In this commit we add the ability to intercept forwarded htlc packets
straight from the RPC layer. The RPC layer handles a bidrectional stream
that comminucates to the client the intercepted packets and handles its
response by coordinating with the interceptable switch.
As part of the preparation to the switch interceptor feature, this
function is changed to return error instead of error channel that
is closed automatically.
Returning an error channel has become complex to maintain and
implement when adding more asynchronous flows to the switch.
The change doesn't affect the current behavior which logs the
errors as before.
This commit extends the link with a new synchronous delivery point for
local UpdateAddHTLC messages. The switch method SendHTLC is updated to
use this delivery point and thereby becomes a synchronous call.
For MPP payments, synchronous hand-off is important. Otherwise the next
pathfinding round could start without the channel balance updated yet.
This fixes an issue where the contract court could leave a completely
swept commit tx unresolved if it was swept by the remote party.
This could happen if (our) commit tx just published was actually a
previously revoked state, in which case the remote party would claim the
funds via a justice transaction.
This manifested itself in the testRevokedCloseRetribution integration
test where at the end of the test Bob was left with a pending channel
that never resolved itself.
